The present invention relates to methods and apparatus for producing a composition material which embodies both the physical and chemical properties of a physically expanded polymer and specific structural and/or chemical properties of solid particles material fully encapsulated within membranes in the expanded polymer.
This invention relates particularly to such methods and apparatus and resulting products wherein numerous variations are possible in characteristics of the resulting product.
My prior U.S. Pat. No. 4,590,218 issued May 20, 1986 and entitled "Method and Apparatus for Forming a Chemical Composition from Cross-Linking Components and Product of the Method" discloses methods and apparatus for varying the density of a chemical composition formed from two liquid components selected for cross-linking reaction with each other.
This U.S. Pat. No. 4,590,218 is incorporated by reference in this application.
In one embodiment disclosed in the U.S. Pat. No. 4,590,218 atomizing means are provided for spraying the product onto the application zone. In one form of this embodiment a sprayed product included abrasive particles for developing negative buoyancy in the resulting product. The abrasive particles were introduced into the pressurized stream of atomizing air used for spraying the product onto the application zone.
The abrasive was added to produce a negative buoyancy, with respect to water, so that the resulting foam material product would have a density greater than 62.4 pounds per cubic foot (the density of water) and could therefore be used as a liner for the bottom of a pond of water without possible problems of the liner floating upwardly from the bottom of the pond.
While this method of introducing abrasive particles into the pressurized air stream used for atomization for spraying applications did produce a uniform distribution of the abrasive in the spray applied polymer, the only purpose of adding the abrasive was to increase the density so as to provide a negative buoyancy. There was no concept in the U.S. Pat. No. 4,590,218 of producing new polymer/particle composition products to incorporate both the physical and chemical properties of the expanded polymer and specific structural and/or chemical properties of added solid particles fully encapsulated in membranes in the expanded polymer.
The method of introducing the abrasive particles into the pressurized atomizing air stream in the U.S. Pat. No. 4,590,218 also has certain limitations. The amount of abrasive, for example, that could be included in polymer in this way was limited, and the abrasive could only be satisfactorily included in certain polymers. The polymer must have a suitably strong structure; otherwise the cells would collapse. And the polymer must not be too fast curing as to prevent injection of the solid particles.
The primary intent of the present invention is to produce new products which are composition materials and which embody both the physical properties of a physically expanded polymer material and specific structural and/or chemical properties of added solid particles which are fully encapsulated within membranes of the expanded polymer material.
The present invention produces unique composition materials of this kind by taking advantage of the flow properties of a liquid, the incompressible properties of a solid, and the compressible properties of a gas.
The present invention takes advantage of these properties by intimately mixing a gas under pressure with a liquid component, allowing that liquid component and entrained pressurized gas to be released in an enclosing chamber and allowing the gas that is entrained in that liquid to expand and to cause the liquid polymer and entrained gas to fill up the available space of the enclosing chamber.
Then, by the addition of solid particles into the compressible gas entrained liquid while the liquid is still in a relaxed state, the method yields a new product offering both the physical and chemical properties of the resin produced from the liquid component material and the specific structural and/or chemical properties that are contributed by the solid particles (e.g., the chemical inertness afforded by solid sand fillers and/or chopped fiberglass, or the swelling properties contributed by bentonite clay, the cushioning properties contributed by rubber material, or high impact or load-bearing properties as contributed by aggregate or abrasive-containing materials).
A liquid material offering the flow properties allows these liquid and added solid materials to be deposited in areas by spray application or by pour.
Since the flow properties based upon the resin (polymer) versus the solid particle content can be varied, it is possible to provide a very tough, resilient, very chemically resistant, finished product--more so than can be obtained with the liquid component material by itself in any of these instances.
The products of the present invention can be provided with properties of either burn resistance or high impact resistance or dielectric or cushioning properties, and all of these products are held together in an appropriate resin binder.
The net effect in each case has been a new product more serviceable than either one of the polymer or filler components of the new product would be by themselves.
Two additional things stand out in the present invention. By filling the enclosing chamber with the gas entrained liquid, the particles are literally immersed into that liquid matrix, and each particle is uniformly coated.
The present invention has been able to achieve densities far greater than could be achieved by manual or mechanical mixing or by any other prior art mixing method that can be compared to the present invention.
In products produced by the present invention there has been no evidence of dry spots. Even the top particles that have been observed still have the evidence of the encapsulating coating on the particles.
An unexpected but very important attribute of the method of the present invention of blending the solid and liquid components is the fact that, as a compressible or yieldable matrix material is filling up the spaces of the enclosing chamber, even the finest of particles, down to 200 mesh particle size, have been uniformly encapsulated and incorporated in the polymer.